You can see above that I changed the value of uri: ( changes in Bold ), and I also changed the file name to icon.png because the filename you were using did not exist in the project you provided. The path that you were using before, file:///images/icon.png, was incorrect and didn't exist.

It appears that the Invocation framework checks to see if the content exists and when it doesn't find it, it just disappears instead of giving any sort of error or feedback message. Hope that helps you and anyone else who might be having trouble.